Hohlraum Simulations of 2-Shock Double Shell Implosions using the LANL xRAGE Code

We present integrated hohlraum simulations of Double Shell implosions [1,2] driven by a 2-shock laser pulse. Double Shells capsules are composed of a low-Z outer shell/ablator

and a high-Z inner shell that contains the fuel. During an implosion, the outer shell converges onto the inner shell and collides with it, transferring energy and momentum. As

the inner shell is set in motion, it compresses the fuel to thermonuclear burn conditions. Since the outer shell is assembled from two hemispheres it contains a small equatorial joint.

If the joint is not sufficiently mitigated, it can be blown open by the hohlraum’s x-ray radiation during the implosion, which reduces implosion symmetry and capsule performance. The 2-shock laser pulse utilizes a picket and main laser pulse that are time separated. This temporal gap allows engineering features like the joint gap to relax and thereby reduces their imprint during an implosion. However, low-mode implosion asymmetries can still arise and need to be addressed with integrated hohlraum simulations. To investigate this, we use LANL’s multi-physics code xRAGE [3,4] which is capable of modeling capsule implosions, including integrated hohlraum simulations. As we compare simulation outcomes to experimental data such as X-ray capsule radiographs and shock timing, we address the effect of different physics and numerical features such as importance of non-local thermal equilibrium assumptions and radiation treatment in our models.

Release number LA-UR-25-27465

[1] D.S. Montgomery et al., Phys. Plasmas 25 (2018)

[2] E.C. Merritt et al., Phys. Plasmas 26 (2019)

[3] M. Gittings et al., Comput. Sci. Disc. 1.1 015005 (2008)

[4] B.M. Haines et al., Phys. Plasmas 29, 083901 (2022)